1. Field of the Invention
The invention relates to a driving force transmission controller and a vehicle control method.
2. Description of the Related Art
Conventionally, there has been known a driving force transmission controller that is mounted in a four-wheel-drive vehicle and that is able to control the amounts of driving forces to be transmitted to right and left wheels independently of each other. For example, Japanese Patent Application Publication No. 10-16600 (JP 10-16600 A) describes such a driving force transmission controller.
The driving force transmission controller described in JP 10-16600 A controls the amounts of driving forces to be transmitted to right and left wheels using a map for high road surface friction resistance and a map for low road surface friction resistance in a mutually complementary manner, depending on a road surface friction coefficient. According to JP 10-16600 A, when a vehicle is in a travelling state in which right and left front wheels, which serve as steered wheels, are steered in a direction opposite to the turning direction during quick turning (counter-steering state), the rotational speed difference between right and left rear wheels is limited on the basis of a lateral acceleration to enhance the turning performance during counter-steering.
However, when the counter-steering state ends and the vehicle is returned to a normal turning state, the details of the process of computing command values of the driving forces to be transmitted to the right and left wheels are changed and thus the driving forces transmitted to the right and left wheels may be rapidly changed. Thus, the vehicle behavior may be temporarily disordered depending on the travelling state of the vehicle.